Our van stopped at a scenic vista on the contour road where verdant mountains undulated southward toward China’s border with Laos. Stepping out to take some photos, I was overcome by an acrid, unpleasant odor. I asked my local travel partner, Xiao Guan, what the stink was.“Money,” he said with a wry smile. “That’s the smell of money, my friend.”He pointed to a small rubber